Planar manifold assembly

ABSTRACT

An analytical instrument preferably in the form of a chromatograph includes a computer, a pneumatic controller responsive to the computer, and planar manifold assembly. The planar manifold assembly includes one or more fluid-handling functional devices that may be surface mounted to a planar manifold. The fluid-handling functional device may be constructed as a valve, operable in response to a control signal from pneumatic controller for controlling fluid flow in selected fluid flow paths in the chromatograph, or as a sensor, a fluid regulator, a fluid flow input or output line, or the like.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for the provisionand control of fluid flow in an analytical apparatus, and moreparticularly with a planar manifold assembly in a gas chromatograph.

BACKGROUND OF THE INVENTION

Analytical instruments which rely upon regulated fluid flow are commonlyemployed in a wide variety of applications, such as sample purification,chemical analysis, clinical assay, and industrial processing. Suchinstruments typically function through devices which operate byinitiating, maintaining, halting, or reversing a flow stream through thedevice. This may be accomplished by combinations of valves and/or pumps.Very often, such instruments devices require multiple flow paths tooperate efficiently. Generally, efficient operation requires a flowsystem combining flow-through components, such as sorbent columns andconnective tubing, with terminal components, such as needles, pumps, anddrains. Different flow paths are frequently required to, for example,isolate a component from the flow system, include a component into theflow system, or rearrange the order of the components in the flowsystem. For many systems, an extensive and complex array of tubing,fittings, and the like are employed to provide the many flow paths thatare necessary for optimum operation.

Combinations of commercially-available valves are often necessary toprovide a number of flow paths among the flow-through components andterminal components employed in a flow system. Further, there is theneed to sense certain characteristics of the fluid flow at differingpoints in the flow paths. Examples of such sensed characteristicsinclude the pressure, flow rate, and temperature of the fluid. Othercharacteristics related to the particular fluid flow include thepresence or absence of a fluid component, such as an analyte orcontaminant. Such needs are typically addressed by the attachment ofdiffering, plural sensors. There exists the practical problem,therefore, of connecting the large number of valves, sensors, fittings,and the like that are required for the multitude of flow pathcombinations in a modern analytical instrument.

Further, such flow systems involve a large number of flow-through andterminal fluid connections which increases the complexity, expense, andphysical volume of the flow system. Such fluid connections are difficultto implement, especially when minimum volumes within the flow system aredesirable. The complexity of such systems also introduces reliabilityconcerns. Because the devices that are implemented in these flow systemsare sometimes automated, the reliability and accessibility of the flowsystem are features critical to successful instrument operation.

Another problem involves the function of properly orienting all of thevalves, sensors, and the like so as to allow the desired combinations offlow paths, yet also provide a flow system that is compact,easily-manufactured, inexpensive, and reliable. For example, theprovision of fluid-tight connections in a complex fluid-handlingassembly has become exceedingly problematic as the assembly is reducedin size. Some instruments, such as a gas chromatograph, employ fluids inthe form of combustible gasses in performing an analysis. Even thoughthe pneumatic fittings in the typical chromatograph are designed tominimize leakage, one may nonetheless consider a pneumatic fault modewherein a gas leak could occur and sufficient gas could accumulate so asto pose an unsafe condition.

It will also be appreciated that a flow system must be versatile, thatis, capable of being reconfigured during an instance of repair ormodification, or to meet the requirements of a particular application asadditional valves, fittings, etc. are added to the flow system.

SUMMARY OF THE INVENTION

The advantages of the invention are achieved in a first preferredembodiment of an analytical instrument, preferably in the form of achromatograph, that includes a computer, a pneumatic controllerresponsive to the computer, and planar manifold assembly. The planarmanifold assembly includes one or more fluid-handling functional devicesattached to a planar manifold. The fluid-handling functional device maybe surface mounted to the planar manifold and may be constructed as avalve, operable in response to a control signal from pneumaticcontroller for controlling fluid flow in selected fluid flow paths inthe chromatograph, or as a sensor, a fluid regulator, a fluid flow inputor output line, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood, and its numerousobjects and advantages will become apparent by reference to thefollowing detailed description of the invention when taken inconjunction with the following drawings, in which:

FIG. 1 is a simplified block diagram of an analytical instrumentconstructed in accordance with the present invention.

FIG. 2 is a side perspective view of preferred embodiment of theanalytical instrument of FIG. 1, constructed as a chromatograph.

FIGS. 3A and 3B are front and rear perspective views, respectively of apreferred embodiment of a planar manifold assembly operable in thechromatograph of FIG. 2.

FIG. 4A is side perspective view of a first exploded portion of a planarmanifold assembly preferred for use in the chromatograph of FIG. 2, andFIG. 4B is side perspective view of a second exploded portion of thesame planar manifold assembly, with certain components of the planarmanifold assembly being common to both FIGS. 4A and 4B for clarity.

FIG. 5A is another side perspective view of the first exploded portionof the planar manifold assembly of FIG. 2, and FIG. 5B is another sideperspective view of the second exploded portion of the same planarmanifold assembly, with certain components of the planar manifoldassembly being common to both FIGS. 5A and 5B for clarity.

FIG. 6 is a side perspective view of the planar manifold operable in theplanar manifold assembly of FIGS. 3-5, illustrating front and backportions of the planar manifold in exploded view for clarity.

FIG. 7 is another side perspective view of the planar manifold of FIG.6, also illustrating the front and back portions of the planar manifoldin exploded view for clarity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will find useful application in a variety ofanalytical systems that benefit from fluid control of one or more fluidstreams. The apparatus and methods of the present invention may beemployed in particular to provide initiation, distribution, redirection,termination, control, sensing, and other types of functions(collectively defined herein as fluid-handling functions) with respectto one or more fluid streams. Gases are the preferred fluids accordingto the practice of the present invention, and therefore the followingdescription of the invention will include a description of thearrangement, construction, and operation of certain pneumatic devices,and hence is particularly directed to the control of a plurality ofgaseous streams in an inlet or detector in a gas chromatographicanalytical system (hereinafter, a chromatograph). However, for thepurposes of the following description, the term "pneumatic" will also beconsidered to refer to all types of fluids.

Further examples that are particularly benefited by use of the presentinvention include supercritical fluid chromatography and high-pressuregas chromatography (HPGC). However, it should be understood that theteachings herein are applicable to other analytical instruments,including liquid chromatographs, high-pressure liquid chromatographs(HPLC), clinical analyzers, flow-injection analyzers, laboratory waterpurification systems, syringe-type reagent dispensers, manual andautomated solid phase extraction (SPE) instruments, supercritical fluidextraction (SFE) instruments, stopped-flow spectrophotometers, automatedprotein or nucleic acid sequencers, and solid phase protein or nucleicacid synthesizers.

A new and novel analytical instrument is shown in FIG. 1 and isgenerally designated chromatograph 10. In order to perform achromatographic separation of a given sample compound, a sample isinjected with a pressurized carrier gas by means of an inlet 12. Thecarrier gas supplied to inlet 12 is provided from a source 12A throughone or more planar manifold assembly(s) 13, each of which serves in partto control and redirect a plurality of gas flows, including the carriergas and a plurality of detector gasses of appropriate types, such asair, hydrogen, and makeup gas. The detector gases are provided fromrespective sources (one such source 24A is shown) to the planar manifoldassembly 13. Suitable fluid-handling functional devices, such asfittings, regulators, valves, sensors, and the like in the planarmanifold assembly 13 may be passive (such as a termination fitting) oractive and hence operated under the control of the computer 22 by way ofcontrol signals provided on a data and control lines 28, 30. Forexample, the pneumatic controller 26 effects control of, among otherthings, fluid flow rate, fluid pressure, fluid flow regulation, and thecontinuity or discontinuity of flow. As further example, the time duringwhich a particular valve in the planar manifold assembly 13 will remainopen and closed in relation to control signals received on the data andcontrol line 28 and in accordance with certain operating conditions ofthe chromatograph 10. The control and data line 30 also allows thereturn of sense information from appropriate signal-interfaceelectronics that connect to the valves, sensors, etc. that are providedin the planar manifold assembly 13. Accordingly, the computer 22,pneumatic controller 26, and planar manifold 13 may be operated toeffect a variety of fluid handling functions that heretofore have beendifficult to achieve in conventional fluid-handling apparatus.

A column 14 is positioned within an oven 16. The carrier gas/samplecombination passing through column 14 is exposed to a temperatureprofile resulting in part from the operation of a heater 18 within oven16. During this profile of changing temperatures, the sample willseparate into its components primarily due to differences in theinteraction of each component with the column 14 at a given temperature.As the separated components exit the column 14, they are detected by adetector 24.

Computer 22 maintains overall control of all systems associated with gaschromatograph 10. It will be recognized that any particular gaschromatograph may include more systems than those described in relationto the present invention. It will also be understood that althoughcomputer 22 is shown as a single block, such computer includes a centralprocessing unit and all associated peripheral devices, such as randomaccess memories, read-only memories, input/output isolation devices,clocks and other related electronic components. In the preferredembodiment, the central processor used in computer 22 is amicroprocessor. As such, computer 22 includes a memory in whichinformation and programming can be stored and retrieved by knownmethods. However, it will be appreciated that the programmed control ofpneumatic controller 26 can be implemented by other computing means,such as an embedded microprocessor or dedicated controller circuitincorporated in the pneumatic controller 26. Also, the programmingassociated with computer 22 that is utilized in relation to the presentinvention will be readily understood from the description herein.

An electronic control panel 50 is shown to include at least two maininput/output components, namely a keypad 58, and a display 60. Bymonitoring the operation of the chromatograph 10 by signals from certaincomponents, such as the detector 24, the computer 22 can initiate andmaintain certain functions required for an analytical run. Consequently,indicating or prompt messages can be generated by computer 22 anddisplayed on display 60. Operating commands and other information areentered into computer 22 by way of keypad 58.

FIG. 2 illustrates a preferred embodiment 100 of the chromatograph 10 ofFIG. 1. In the preferred embodiment, the chromatograph 100 is aHewlett-Packard HP6890 gas chromatograph. The chromatograph 100 includesan inlet port fan 102 and respective cover 102C, an inlet port section103 and respective cover 103C, a pneumatics section 104 and respectivecover 104C, a detector section 105 and respective cover 105C, and anelectronics section 106A and respective cover 106C. According to afeature of the present invention, the pneumatics section 104 includesprovision for the installation and operation of a plurality of theplanar manifold assembly 13 of FIG. 1. In particular, the plurality mayinclude a first planar manifold assembly 110 specifically designed foruse in fluid-handling functions that relate to one or more detectors 24,and second planar manifold assembly 120 designed for use influid-handling functions that relate to one or more inlets 12. Thus, andin accordance with another feature of the present invention, the planarmanifold assembly 13 may be configured to perform fluid-handlingfunctions for a specific portion of the chromatograph 100.

FIGS. 3-5 illustrate in greater detail the second planar manifoldassembly 120 of FIG. 2. The illustrated embodiment is accordinglyconstructed for use with the inlet 12 of the chromatograph 10 of FIG. 2.With reference again to FIG. 1, however, it should be understood thatthe description and teachings herein may be applied as well to theconstruction of a planar manifold assembly for use with fluid-handlingfunctions associated with the operation of the detector 24, the column14, or another portion of the chromatograph 10.

The second planar manifold assembly 120 includes a planar manifold 210,an inlet manifold chassis 220, a first valve 231, a second valve 232, athird valve 233, a valve clamp 240, a fitting block 250, and a supplyfitting 260. The fitting block includes a longitudinal port surface 251,a first lateral port surface 252, a second lateral port surface 254, andan upper port surface 255. A split vent line 262 and a septum purge ventline 263 are attachable to respective vents 264, 265 in the upper portsurface 255 in fitting block 250. The second planar manifold assembly120 includes a valve backing plate 310, a data and control signalinterface board 320, a flow controller 330, a first sensor 341, and asecond sensor 342.

In the preferred embodiment, the first valve 231 is constructed as asolenoid valve; the second valve 232 and the third valve 233 are eachconstructed as proportional valves; the flow controller 330 isconstructed as a purge flow controller; and the first sensor 341 isconstructed as a pressure sensor and the second sensor 342 isconstructed as a flow sensor. Further, the supply fitting 260 isconstructed to receive carrier gas from a supply line (not shown) at asupply line fitting 266. The supply fitting 260 attaches to the firstlateral port surface 252 in the fitting block 250 so as to transfer aflow of carrier gas from a through hole 261 into a port (not shown) onthe first lateral port surface 252 in the fitting block 250. The supplyfitting also includes an internal frit (not shown). That is, the fittingblock 250 is constructed to include a plurality of internal,fluid-bearing passageways that are accessible at respective ports onseveral of the surfaces of the fitting block 250.

Each port on the fitting block 250 is recessed to allow use of O-ring270 for face-sealing the planar manifold 210, or a particularfluid-handling functional device, to the fitting block 250. For example,a septum purge line port 267, a carrier gas port 268, and a split ventline port 269 are located in the second lateral port surface 254 andreceive respective O-rings 270; a plurality of ports in the firstlongitudinal port surface 251 receive respective O-rings 270 when matedto respective ports 212 on the planar manifold 210.

The inlet manifold chassis 220 aids in aligning the fitting block 250and the valves 231, 232, 233 to the planar manifold 210. The first valve231, second valve 232, and third valve 233 are clamped to the planarmanifold 210 by the valve clamp 240 with the aid of suitable means knownin the art, such as fasteners (not shown), that pass through the valvebacking plate 310 and appropriate through-holes in the planar manifold210, so as to be secured by suitable means, such as threaded apertures,in the valve clamp 240. The respective valve block faces 235, 236, 237are thus face-sealed to the planar manifold 210. The longitudinal portsurface 251 of the fitting block 250 is similarly clamped to the planarmanifold 210 by way of suitable fasteners (not shown).

FIGS. 6 and 7 illustrate a preferred embodiment of a planar manifold 600contemplated by the present invention. A front plate 602A and a backplate 602B may be seen to be sized and constructed to be superimposedand bonded together during the manufacturing process to form the planarmanifold 600. Preferably, the front plate 602A and back plate 602B arepreferably machined from stainless steel and etched to provide anarrangement of features, discussed below, before being bonded together.The preferred method of bonding is diffusion bonding, which generally isknown in the art and is described in, for example, U.S. Pat. No.3,530,568, the disclosure of which is included herein by reference.However, in other embodiments, other materials and bonding methods maybe employed, and a number of etched intermediary plates (such as one,two, or more, not shown) are also contemplated being providedintermediate the front plate 602A and back plate 602B to form amulti-layer configuration.

A notch 604B in the rear plate 602B is included at manufacture tocorrespond with one of several indicia 604A inscribed on the front plate602A so as to define a particular pneumatic configuration that is servedby the planar manifold 600. In the illustrated embodiment, the notch604B indicates by its location that the planar manifold 600 is intendedfor use in a split/splitless (S/SL) inlet configuration, and accordinglythe description herein is directed to the planar manifold assembly 120constructed for use in a chromatograph 10 having such an inletconfiguration. Upon modifications to the back plate 602B, there arecontemplated other preferred embodiments of the planar manifold assembly120 that are designed for use in cool on-column (COC) or purged pack(PP) inlet configurations. It is a feature of the present invention thatthe construction of the front plate 602A is common to all of the namedinlet configurations, and that the back plate 602B will vary in itsconstruction according to the type of inlet configuration that is to beserved. This feature thus makes the front plate 602A a more versatilepiece part, thus lowering the parts count and reducing manufacturingcosts. In addition, the location of the notch 604B can be sensed duringassembly of the planar manifold assembly to ensure that the planarmanifold 210 has been properly configured for the particular inletconfiguration.

Each of the front plate 602A and the rear plate 602B include a varietyof other physical features for accommodating certain mechanicalfunctions. Notches 605A and 605B serve to accommodate a locatingprotrusion (not shown) on the inlet manifold chassis 220 for mountingthe data and control signal interface board 320. Oblong openings 606A,606B are distributed longitudinally to effect a thermal break betweenthe plate upper portions 608A, 608B and the plate lower portions 610A,610B. Locator holes 611A, 611B are provided for locating the planarmanifold 600 on respective protrusions (not shown) on the inlet manifoldchassis 220; tooling holes 612A, 612B are used during construction ofthe planar manifold 600. Through-holes 614A, 614B allow passagetherethrough of the fasteners used to clamp the valve clamp 240 to thevalve backing plate 310, and through-holes 615A, 615B allow a protrusionon the inlet manifold chassis 220 to support the data and control signalinterface board 320. Clearance holes 616A, 616B are provided foraccommodating respective protrusions (not shown) on the inlet manifoldchassis 220 so as to properly orient the valve backing plate 310.

Plate upper portions 608A, 608B include several features common to bothpieces so as to receive certain fluid-handling functional devicesalready described. In particular, to accommodate attachment of the flowsensor 342, there are provided: fastener through-holes 622A, 622B; apneumatic output 624A and a corresponding first minor pneumatic channel624B; pneumatic input 625A and corresponding first major pneumaticchannel 625B; locating holes 626A, 626B to accommodate a protrusion342P; and fastener through-holes 628A, 628B. To accommodate attachmentof the pressure sensor 341, there are provided: a pneumatic output 634Aand a corresponding third minor pneumatic channel 634B; locating holes636A, 636B that accommodate plural protrusions 341P; and fastenerthrough-holes 638A, 638B. To accommodate attachment of the purge flowcontroller 330, there are provided: fastener holes 642A, 642B, 644A,644B; a pneumatic input 646A which communicates with the third minorpneumatic channel 634B; and pneumatic outputs 648A, 648B whichcommunicate with a channel in the fitting block 250.

In addition to the first major pneumatic channel 625B, theta is a secondmajor pneumatic channel 652, a third major pneumatic channel 653, and afourth major pneumatic channel 654. The fourth major pneumatic channel654 communicates with the fitting block 250 at an upper output 655 andalso communicates with the first valve 231 at a lower output 662. Thesecond major pneumatic channel 657 communicates with the fitting block250 at an upper output 656 and also communicates with the second valve232 at a lower output 663. The first major pneumatic channelcommunicates with the pneumatic input 625A and the third valve 233 at alower output 665. The third major pneumatic channel 653 communicateswith the first valve 231 at an upper output 661, and also communicateswith the second valve 232 at a lower output 664. A second minorpneumatic channel 684 communicates with a carrier gas input 671 and thethird valve 233 at a lower output 666. The first minor pneumatic channel624B also communicates with the fitting block 250 at an upper output667. The third minor pneumatic channel 634B communicates with thefitting block 250 at an upper output 668.

The advantages of the planar manifold assembly of the present inventioninclude the reduction of external connections between fluid-handlingfunctional devices (such as fittings, valves, sensors, and the like) byuse of a single planar manifold for the provision of a plurality of flowpaths. The fluid-handling functional devices that connect to the planarmanifold are preferably constructed to be surface-mounted, which hasbeen found to offer reliable, fluid-tight connection without thecomplexity and difficulty of conventional pneumatic connections. Thenumber and complexity of external connections, which would otherwiseundesirably increase the volume of the flow system, are also decreased.Another advantage is that the reliability of the pneumatic connectionsis improved.

A further advantage of the present invention is that multiplefluid-handling functional devices may be coordinated and assembled in asmaller volume than is possible in prior art systems. This results fromthe pneumatic channels that are integrated in the planar manifold, andthus many of the fluid flow paths are integral to the planar manifold,which is itself quite compact and amenable to construction in a varietyof shapes and configurations. For example, it is contemplated that theplanar manifold may be constructed in an irregular shape, such as acurved, bent, or multiply-angled configuration, so as to conform to anirregularly-shaped, compact volume.

A large number of fluid-handling functional paths may be integrated intothe planar manifold that heretofore would be difficult if not impossibleto assemble using traditional tubular pipe, ferrules, and manualfittings. Also, considerable cost savings and improved reliability arerealized by reduction of the number of connections necessary to achievemultiple flow paths.

The surface-mounted pneumatic connections provided by the invention alsoreduce the complexity of a flow system, which is desirable during thestages of manufacturing, assembly, repair, or modification of theanalytical instrument in which the planar manifold assembly may besituated.

While the invention has been described and illustrated with reference tospecific embodiments, those skilled in the art will recognize thatmodification and variations may be made without departing from theprinciples of the invention as described herein above and set forth inthe following claims.

What is claimed is:
 1. A planar manifold assembly constructed for use inperforming a plurality of fluid-handling functions with respect to afluid flow in a selected portion of an analytical instrument,comprising:a planar manifold including first and second plates, each ofsaid plates having inner and outer surfaces, said first plate having afirst plurality of pneumatic channels located in its respective innersurface, and a third plate having first and second surfaces respectivelybonded to portions of the inner surfaces of the first and second plates,respectively, wherein the second surface of the third plate furthercomprises a second plurality of pneumatic channels, said outer surfacesforming respective first and second planar manifold outer surfaces, andselected ones of said pneumatic channels communicating with selectedones of the first and second planar manifold outer surfaces atrespective manifold ports; a plurality of fluid-handling functionaldevices for performing respective fluid-handling functions, each of thefluid-handling functional devices having a device port; and means forsurface mounting the device port to a selected one of the manifold portsso as to effect a fluid-tight connection between the device port and theselected manifold port; wherein said plurality of fluid-handlingfunctions is performed according to a predetermined configuration of thefluid-handling devices, the pneumatic channels, and the manifold ports.2. The planar manifold assembly of claim 1, wherein the selected portionof the analytical instrument is an inlet and the configuration ispredetermined according to the path of the fluid flow in the inlet andthe pneumatic channels.
 3. The planar manifold assembly of claim 1,wherein the selected portion of the analytical instrument is a detectorand the configuration is predetermined according to the path of thefluid flow in the detector and the pneumatic channels.
 4. The planarmanifold assembly of claim 1, wherein the selected portion of theanalytical instrument is a separation column and the configuration ispredetermined according to the path of the fluid flow in the separationcolumn and the pneumatic channels.
 5. The planar manifold assembly ofclaim 1, wherein the device port is situated on a planar face in thefluid handling device, and said surface mounting means further comprisesmeans for superimposing the device port on said selected one of themanifold ports and for removably attaching the planar face to theselected outer planar surface manifold surface.
 6. The planar manifoldassembly of claim 1, wherein the plurality of fluid-handling functionaldevices includes a first fluid-handling functional device for performinga first fluid-handling function and a second fluid-handling-functionaldevice for performing a second, differing fluid-handling function, andwherein each of said first fluid-handling functional device and saidsecond fluid-handling functional device is selected from a groupincluding: valves, sensors, flow controllers, and fluid fittings.
 7. Theplanar manifold assembly of claim 1, wherein the performance of one ofsaid fluid handling functions by a respective fluid-handling functionaldevice is associated with an electronic signal, and further comprising asignal interface board operably connected to the respectivefluid-handling functional device for interfacing the electronic signal.8. The planar manifold assembly of claim 1, wherein at least one of thefirst, second, and third plates is formed of metal.
 9. The planarmanifold assembly of claim 1, wherein portions of the inner surfaces ofthe first and second plates further comprise a material susceptible tobonding by a diffusion bonding process, and wherein the first, second,and third plates are bonded together according to the diffusion bondingprocess.
 10. The planar manifold assembly of claim 1, wherein at leastone of the first and second plates includes indicia representative ofthe predetermined configuration.